Interactions of Hydrophobia Layer Silicates with Alcohol‐Benzene Mixtures I. Adsorption Isotherms

Abstract

Abstract A model isotherm is developed that describes the adsorption of methanol and benzene from methanol‐benzene mixtures throughout the whole concentration range (molar fraction of methanol from x 1 = 0 to x 1 = 1). The clay mineral montmorillonite is used as an adsorbent. The silicate layers are made hydrophobia by exchanging the inorganic gegen ions by alkylammonium ions C nc H 2nc + 1 NH 3 + ( n c = 10—18). With increasing alkyl chain length (increasing hydrophobicity) the amounts of benzene adsorbed ( n s 2 ) increase, whereas those of methanol ( n s 1 ) remain constant. The adsorption potential η 1 of methanol decreases and that of benzene (ζ 2 ) increases with the alkyl chain length. The difference η 2 —η 1 changes from positive to negative at n c = 16. Besides the influence of the alkyl chain length, the shape of the excess isotherms and the azeotropic compositions are mainly determined by the bulk‐phase activities.